Can't Upload a Map

Hello, I'm trying to upload some maps that I have and it won't work.  I go into my game, go to the library, click to upload and select the file.  Then, no matter what I do it just will not give me a prompt to confirm the upload. All it does is create a grey line in the box. I have tried everything I can think of, including using a different browser with no luck. Am I missing something?

Ensure that the file is of a supported format. If it is a jpeg, ensure that the extension is ".jpg" not ".jpeg". Also, what is the file size. There is an upload limit. I believe it is 10MB for a free user, though in practice it's a bit smaller to account for processing overhead.

Okay great. Thank you very much for the response I will try these things out tonight

You were correct.  I didn't realize how huge the map files were.  I had to photoshop down the size and resolution but they still look great and loaded quickly.  Thank you very much.